Silver, as an antimicrobial agent, continues to be a growing area of interest across many industries such as, medicinal, pharmaceutical and aeronautical, although silver has traditionally been valued for its ductility and luster. For instance, silver nitrate has been used for treating eye diseases in infants, while silver sulfadiazine has been used for topical administration in the healthcare industry. As understood, these compounds take advantage of enhanced potency of the silver (Ag+) ion against microbes, while leaving eukaryotic cells unharmed when applied topically at microbicidal concentrations. For instance, silver (Ag+) ion binds to sulfur and/or phosphorus atoms within a cell, disrupting protein and DNA structures, which, for instance, leads to inhibition of essential cellular processes, membrane disruption, and DNA damage. This, for instance, eventually results in the death of the cell. In another example, silver also induces decoupling of the respiratory chain, leading to cell death.
Additionally, owing to their antimicrobial characteristics, silver or silver-containing products are often utilized as antimicrobial coatings over surfaces, such as, toilet handles, pens, door knobs, and aircraft surfaces, to minimize fomite-mediated transmission of microbes. Disadvantageously, silver coatings cause discolorations, (for example, unpleasant dark brown to grey color) of such surfaces, due to aggregation of silver particles which, for instance, leads to a strong plasmon signal. As understood, metallic silver exhibits high plasmonic efficiency, due to collective oscillation of valence electrons of silver, when an incident photon matches the resonant frequencies of the valence electrons, leading to emission of that energy as a photon which, for instance, can be confirmed by a strong silver peak in its corresponding UV-Visible spectrum.
Accordingly, there exists a continuing need for developing novel silver-containing products that remain colorless (for instance, visibly indistinguishable from an untreated surface, upon coating), without compromising its antimicrobial efficacy.